Method and apparatus for adaptive indirect carrier modulation

ABSTRACT

A wireless transmit/receive unit, WTRU, can select a constellation from a set of constellations corresponding to a symbol configuration for indirect carrier modulation, ICM, based on at least one constellation performance efficacy indicator, each constellation performance efficacy indicator respectively corresponding to a constellation of the set of constellations, and use the selected constellation and symbol configuration to simultaneously harvest energy and transmit data.

BACKGROUND

Indirect carrier modulation methods have the potential to enableultra-low power transmitters that can be deployed in large scale.Existing systems that employ indirect carrier modulation includeNear-field communication (NFC) and Radio-frequency identification(RFID).

In RFID, a so-called reader can interact with a plurality of devices(“tags”). The reader provides over-the-air Radio Frequency (RF) powerand data to the tags on the downlink (DL). The tags use the RF powerprovided by the reader to send data back. The tags transmit data bymodulating their antenna loads using simple schemes—e.g. On-Off Keying(OOK) and Binary Phase Shift Keying (BPSK)—and reflect the RF carriertransmitted by the reader back to the reader. Passive RFID devicestypically use OOK modulation on the uplink, which is well suited forenergy harvesting on the downlink, while semi-passive and active devicesemploy for example BPSK that is well suited for transmitting higherenergy per bit in an indirect carrier modulation framework. A particularproduct supports a single frequency band and communication mode. Thereader and all tags communicate over the same frequency channel. Thus, atag performs power reception on the DL and data transmission on theuplink (UL) simultaneously using the same carrier frequency.

RFID systems use indirect carrier modulation transmission betweenbackscatter coupled devices where the reader and tag are in the farfield of each other's antennas. RFID tags can be passive (i.e. withoutautonomous power source), semi-passive (i.e. with a small battery) oractive (i.e. with an autonomous power source, such as a battery).Existing RFID standards specify only one mode of communication. This isreferred to as the reader/writer mode where the reader initiates allcommunication by interrogating the tags. The tags respond only wheninterrogated by the reader. Existing RFID standards specify severalfrequency bands, ranging from low frequency (125 kHz) to super-highfrequency, SHF (5.8 GHz). RFID communication range can extend up to 100m.

NFC can be said to be a refined version of RFID. It is used forapplications as varied as home automation, consumer electronics andsmart meters. NFC systems use indirect carrier modulation transmissionbetween inductively coupled devices where the reader and tag are in thenear field of each other's transducers. NFC devices can be passive,semi-passive or active. Existing NFC standards specify a singlefrequency band, 13.56 MHz, and three modes ofcommunication—“reader/writer”, “card emulation” and “peer-to-peer”. NFCcommunication range extends from roughly one centimeter up to one meter.

SUMMARY

A method and apparatus for operation by a wireless transmit/receiveunit, WTRU. The WTRU may select a constellation from a set ofconstellations corresponding to a symbol configuration for indirectcarrier modulation, ICM, based on at least one constellation performanceefficacy indicator, each constellation performance efficacy indicatorrespectively corresponding to a constellation of the set ofconstellations, and use the selected constellation and symbolconfiguration, simultaneously harvesting energy and transmitting data.

BRIEF DESCRIPTION OF THE DRAWINGS

Furthermore, like reference numerals in the figures indicate likeelements, and wherein:

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram illustrating an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to an embodiment;

FIG. 1C is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to an embodiment;

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to an embodiment;

FIG. 2A and 2B respectively illustrate first-order indirect carriermodulation schemes and the associated 2-point constellations using OOKand BPSK;

FIGS. 3A and 3B respectively illustrate examples of second orderindirect carrier modulation schemes and the associated 4-pointconstellations using QPSK and 4-QAM;

FIGS. 4A and 4B illustrate the ICM state transitions and the transmittedwaveform associated with a commonly used Manchester-encoded OOK indirectcarrier modulation scheme;

FIGS. 5A and 5B illustrate another example of a Manchester-encodedindirect carrier modulation scheme employing BPSK to transmit one bitper symbol;

FIGS. 6A and 6B illustrate a hybrid phase-amplitude indirect carriermodulation scheme according to an embodiment of the present principles;

FIGS. 7A and 7B illustrate a decoding scheme for hybrid phase-amplitudeindirect carrier modulation transmission according to an embodiment ofthe present principles;

FIGS. 8A-8C illustrate an example of a sparse block code;

FIGS. 9A-9C illustrate sparse block code according to an embodiment ofthe present principles;

FIG. 10 illustrates an embodiment of a method according to of thepresent principles;

FIG. 11 illustrates a further embodiment of a method according to of thepresent principles;

FIG. 12 illustrates a further embodiment of a method according to of thepresent principles;

FIG. 13 illustrates a further embodiment of a method according to of thepresent principles;

FIGS. 14-19 illustrate examples of possible transmissions methodaccording to embodiments of the present principles;

FIGS. 20A and 20B illustrate sparse block coding scheme embodiments;

FIGS. 21A and 21B illustrate an example of a dense block code and theassociated carrier modulation scheme;

FIG. 22 illustrates a time domain description of transmitted waveformscorresponding to certain dense block codes;

FIGS. 23A and 23B illustrate dense block coding scheme embodiments;

FIG. 24 illustrates a further embodiment of a method according to thepresent principles; and

FIG. 25 illustrates a further embodiment of a method according to thepresent principles.

EXAMPLE NETWORKS FOR IMPLEMENTATION OF THE EMBODIMENTS

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM(UW-OFDM), resource block-filtered OFDM, filter bank multicarrier(FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network (CN) 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d, any of which maybe referred to as a “station” and/or a “STA”, may be configured totransmit and/or receive wireless signals and may include a userequipment (UE), a mobile station, a fixed or mobile subscriber unit, asubscription-based unit, a pager, a cellular telephone, a personaldigital assistant (PDA), a smartphone, a laptop, a netbook, a personalcomputer, a wireless sensor, a hotspot or Mi-Fi device, an Internet ofThings (IoT) device, a watch or other wearable, a head-mounted display(HMD), a vehicle, a drone, a medical device and applications (e.g.,remote surgery), an industrial device and applications (e.g., a robotand/or other wireless devices operating in an industrial and/or anautomated processing chain contexts), a consumer electronics device, adevice operating on commercial and/or industrial wireless networks, andthe like. Any of the WTRUs 102 a, 102 b, 102 c and 102 d may beinterchangeably referred to as a UE.

The communications systems 100 may also include a base station 114 aand/or a base station 114 b. Each of the base stations 114 a, 114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to oneor more communication networks, such as the CN 106, the Internet 110,and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a Node-B, an eNode B,a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, anaccess point (AP), a wireless router, and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals on one or morecarrier frequencies, which may be referred to as a cell (not shown).These frequencies may be in licensed spectrum, unlicensed spectrum, or acombination of licensed and unlicensed spectrum. A cell may providecoverage for a wireless service to a specific geographical area that maybe relatively fixed or that may change over time. The cell may furtherbe divided into cell sectors. For example, the cell associated with thebase station 114 a may be divided into three sectors. Thus, in oneembodiment, the base station 114 a may include three transceivers, i.e.,one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and mayutilize multiple transceivers for each sector of the cell. For example,beamforming may be used to transmit and/or receive signals in desiredspatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink(DL) Packet Access (HSDPA) and/or High-Speed Uplink (UL) Packet Access(HSUPA).

In an embodiment, the base station 114 a in the RAN 104 and the WTRUs102 a, 102 b, 102 c may implement a radio technology such as EvolvedUMTS Terrestrial Radio Access (E-UTRA), which may establish the airinterface 116 using Long Term Evolution (LTE) and/or LTE-Advanced(LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a in the RAN 104 and the WTRUs102 a, 102 b, 102 c may implement a radio technology such as NR RadioAccess, which may establish the air interface 116 using New Radio (NR).

In an embodiment, the base station 114 a in the RAN 104 and the WTRUs102 a, 102 b, 102 c may implement multiple radio access technologies.For example, the base station 114 a and the WTRUs 102 a, 102 b, 102 cmay implement LTE radio access and NR radio access together, forinstance using dual connectivity (DC) principles. Thus, the airinterface utilized by WTRUs 102 a, 102 b, 102 c may be characterized bymultiple types of radio access technologies and/or transmissions sentto/from multiple types of base stations (e.g., a eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106.

The RAN 104 may be in communication with the CN 106, which may be anytype of network configured to provide voice, data, applications, and/orvoice over internet protocol (VoIP) services to one or more of the WTRUs102 a, 102 b, 102 c, 102 d. The data may have varying quality of service(QoS) requirements, such as differing throughput requirements, latencyrequirements, error tolerance requirements, reliability requirements,data throughput requirements, mobility requirements, and the like. TheCN 106 may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the CN 106 may be in direct or indirectcommunication with other RANs that employ the same RAT as the RAN 104 ora different RAT. For example, in addition to being connected to the RAN104, which may be utilizing a NR radio technology, the CN 106 may alsobe in communication with another RAN (not shown) employing a GSM, UMTS,CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN 106 may also serve as a gateway for the WTRUs 102 a, 102 b, 102c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP internet protocol suite. Theother networks 112 may include wired and/or wireless communicationsnetworks owned and/or operated by other service providers. For example,the other networks 112 may include another CN connected to one or moreRANs, which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1A may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad 128, non-removable memory 130, removable memory 132,a power source 134, a chipset 136 for a positioning system such asGlobal Positioning System (GPS), and/or other elements 138, amongothers. It will be appreciated that the WTRU 102 may include anysub-combination of the foregoing elements while remaining consistentwith an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a in FIG. 1A) over the air interface 116. For example, in oneembodiment, the transmit/receive element 122 may be an antennaconfigured to transmit and/or receive RF signals. In an embodiment, thetransmit/receive element 122 may be an emitter/detector configured totransmit and/or receive IR, UV, or visible light signals, for example.In yet another embodiment, the transmit/receive element 122 may beconfigured to transmit and/or receive both RF and light signals. It willbe appreciated that the transmit/receive element 122 may be configuredto transmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 1B as asingle element, the WTRU 102 may include any number of transmit/receiveelements 122. More specifically, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as NR and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, and/or thedisplay/touchpad 128. In addition, the processor 118 may accessinformation from, and store data in, any type of suitable memory, suchas the non-removable memory 130 and/or the removable memory 132. Thenon-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other elements 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the elements 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The elements 138 may include one or moresensors, the sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor; an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, and/ora humidity sensor.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) anddownlink (e.g., for reception) may be concurrent and/or simultaneous.The full duplex radio may include an interference management unit toreduce and or substantially eliminate self-interference via eitherhardware (e.g., a choke) or signal processing via a processor (e.g., aseparate processor (not shown) or via processor 118). In an embodiment,the WRTU 102 may include a half-duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for either the UL (e.g., for transmission) or thedownlink (e.g., for reception)).

FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the CN 106.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160 b, 160 c may communicate with one another over an X2 interface.

The CN 106 shown in FIG. 1C may include a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (or PGW) 166. While each of the foregoing elements are depictedas part of the CN 106, it will be appreciated that any of these elementsmay be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 162 a, 162 b, 162 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 104 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 102 b, 102 c, managing and storing contexts of theWTRUs 102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 106 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 106 and thePSTN 108. In addition, the CN 106 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have an access or an interface to a DistributionSystem (DS) or another type of wired/wireless network that carriestraffic into and/or out of the BSS. Traffic to STAs that originates fromoutside the BSS may arrive through the AP and may be delivered to theSTAs. Traffic originating from STAs to destinations outside the BSS maybe sent to the AP to be delivered to respective destinations. Trafficbetween STAs within the BSS may be sent through the AP, for example,where the source STA may send traffic to the AP and the AP may deliverthe traffic to the destination STA. The traffic between STAs within aBSS may be considered and/or referred to as peer-to-peer traffic. Thepeer-to-peer traffic may be sent between (e.g., directly between) thesource and destination STAs with a direct link setup (DLS). In certainrepresentative embodiments, the DLS may use an 802.11e DLS or an 802.11ztunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may nothave an AP, and the STAs (e.g., all of the STAs) within or using theIBSS may communicate directly with each other. The IBSS mode ofcommunication may sometimes be referred to herein as an “ad-hoc” mode ofcommunication.

When using the 802.11ac infrastructure mode of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling.The primary channel may be the operating channel of the BSS and may beused by the STAs to establish a connection with the AP. In certainrepresentative embodiments, Carrier Sense Multiple Access with CollisionAvoidance (CSMA/CA) may be implemented, for example in in 802.11systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, maysense the primary channel. If the primary channel is sensed/detectedand/or determined to be busy by a particular STA, the particular STA mayback off. One STA (e.g., only one station) may transmit at any giventime in a given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. Thechannel operating bandwidths, and carriers, are reduced in 802.11af and802.11ah relative to those used in 802.11n, and 802.11ac. 802.11afsupports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications (MTC), such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode), transmitting to the AP, the entire available frequency bands maybe considered busy even though a majority of the frequency bands remainsidle and may be available.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 1D is a system diagram illustrating the RAN 113 and the CN 115according to an embodiment. As noted above, the RAN 113 may employ an NRradio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The RAN 113 may also be in communication with theCN 115.

The RAN 113 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 113 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 180 b, 180 c may utilize beamforming to transmit signals toand/or receive signals from the WTRUs 102 a, 102 b, 102 c. Thus, the gNB180 a, for example, may use multiple antennas to transmit wirelesssignals to, and/or receive wireless signals from, the WTRU 102 a. In anembodiment, the gNBs 180 a, 180 b, 180 c may implement carrieraggregation technology. For example, the gNB 180 a may transmit multiplecomponent carriers (not shown) to the WTRU 102 a. A subset of thesecomponent carriers may be on unlicensed spectrum while the remainingcomponent carriers may be on licensed spectrum. In an embodiment, thegNBs 180 a, 180 b, 180 c may implement Coordinated Multi-Point (CoMP)technology. For example, WTRU 102 a may receive coordinatedtransmissions from gNB 180 a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containingvarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c inFIG. 1C). In the standalone configuration, WTRUs 102 a, 102 b, 102 c mayutilize one or more of gNBs 180 a, 180 b, 180 c as a mobility anchorpoint. In the standalone configuration, WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using signals in an unlicensedband. In a non-standalone configuration WTRUs 102 a, 102 b, 102 c maycommunicate with/connect to gNBs 180 a, 180 b, 180 c while alsocommunicating with/connecting to another RAN such as eNode-Bs 160 a, 160b, 160 c. For example, WTRUs 102 a, 102 b, 102 c may implement DCprinciples to communicate with one or more gNBs 180 a, 180 b, 180 c andone or more eNode-Bs 160 a, 160 b, 160 c substantially simultaneously.In the non-standalone configuration, eNode-Bs 160 a, 160 b, 160 c mayserve as a mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a,180 b, 180 c may provide additional coverage and/or throughput forservicing WTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, dual connectivity, interworkingbetween NR and E-UTRA, routing of user plane data towards User PlaneFunction (UPF) 184 a, 184 b, routing of control plane informationtowards Access and Mobility Management Function (AMF) 182 a, 182 b andthe like. As shown in FIG. 1D, the gNBs 180 a, 180 b, 180 c maycommunicate with one another over an Xn interface.

The CN 115 shown in FIG. 1D may include at least one AMF 182 a, 182 b,at least one UPF 184 a, 184 b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whileeach of the foregoing elements are depicted as part of the CN 115, itwill be appreciated that any of these elements may be owned and/oroperated by an entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different protocol data unit (PDU)sessions with different requirements), selecting a particular SMF 183 a,183 b, management of the registration area, termination of NASsignaling, mobility management, and the like. Network slicing may beused by the AMF 182 a, 182 b in order to customize CN support for WTRUs102 a, 102 b, 102 c based on the types of services being utilized WTRUs102 a, 102 b, 102 c. For example, different network slices may beestablished for different use cases such as services relying onultra-reliable low latency (URLLC) access, services relying on enhancedmassive mobile broadband (eMBB) access, services for MTC access, and/orthe like. The AMF 162 may provide a control plane function for switchingbetween the RAN 113 and other RANs (not shown) that employ other radiotechnologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP accesstechnologies such as WiFi.

The SMF 183 a, 183 b may be connected to an AMF 182 a, 182 b in the CN115 via an N11 interface. The SMF 183 a, 183 b may also be connected toa UPF 184 a, 184 b in the CN 115 via an N4 interface. The SMF 183 a, 183b may select and control the UPF 184 a, 184 b and configure the routingof traffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b mayperform other functions, such as managing and allocating UE IP address,managing PDU sessions, controlling policy enforcement and QoS, providingdownlink data notifications, and the like. A PDU session type may beIP-based, non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering downlink packets, providing mobility anchoring, and thelike.

The CN 115 may facilitate communications with other networks. Forexample, the CN 115 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 115 and the PSTN 108. In addition, the CN 115may provide the

WTRUs 102 a, 102 b, 102 c with access to the other networks 112, whichmay include other wired and/or wireless networks that are owned and/oroperated by other service providers. In one embodiment, the WTRUs 102 a,102 b, 102 c may be connected to a local Data Network (DN) 185 a, 185 bthrough the UPF 184 a, 184 b via the N3 interface to the UPF 184 a, 184b and an N6 interface between the UPF 184 a, 184 b and the DN 185 a, 185b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d, Base Station 114 a-b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-b, UPF 184a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation devices may performthe one or more, or all, functions while being fully or partiallyimplemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or may performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

DETAILED DESCRIPTION

A key challenge for future cellular communication is the need to supporttrillions of connected and often mobile devices. While cellular datarates have experienced a tremendous increase over the past three decades(close to 6 orders of magnitude), there has been less than ten timesimprovement in battery energy density from 1990 to 2015. This presents amajor challenge in scaling to one trillion devices. As an example,assuming one trillion deployed devices, each with a 10-year batterylife, this would result in an average of 274 million battery changes perday. Furthermore, in some cases, changing the battery will be difficult,if not impossible. Therefore, scaling to one trillion devices could bewell served by re-imagining the radio transceiver, the air-interface andthe overall system.

Some key advances that could assist this scaling include ultra-low powerRF transmitters capable of supporting at least small cell-like linkbudgets, zero-energy uplink air-interfaces that do not draw power fromthe device's battery with the goal of enabling “for-ever” batteries inthe near term and battery-free operation of devices in the long term,and a scalable system framework that can support a diverse set ofdeployment scenarios and device types.

An indirect carrier modulation-based backscatter coupled communicationframework, used for example in far-field RFID systems, could be helpfulwhen integrating legions of mobile connected devices into mobilecommunication networks (e.g. future 3GPP and IEEE networks). To thisend, ultra-low-power transponders for terminal devices that are capableof communication ranges extending from a few tens of meter to a fewhundreds of meters could be useful. These transponders could supportmultiple modes of operation and be able to adapt dynamically indifferent operating environments. Such devices could benefit from moresophisticated coded modulation methods (as compared to those currentlyspecified for e.g. RFID systems) while the power consumption and costare limited. Furthermore, these devices would also benefit from beingpowered over-the-air by the network.

Somewhat simplified, a transponder using indirect carrier modulation caninclude an antenna, an indirect carrier modulator (ICM) with aprogrammable antenna load and a load modulator, a memory module to storea payload, an energy harvester and a battery, possibly with a levelindicator. Data is transmitted on the UL by reflecting the incident wavein accordance with the payload. The antenna load in the ICM can beconfigured to different impedance states and the antenna load modulatorcan configure the antenna load dynamically in accordance with specifiedmodulation type and payload.

The antenna load determines both the transmitted energy and theharvested energy. If the power of the incident RF signal is P_(IN) andthe antenna load is configured to power reflectance coefficient of Γ,then the harvested power is (1−Γ)P_(IN)λ, where λ<1 is the powerconversion efficacy of the energy harvester. The transmitted orreflected energy is ΓP_(IN).

Currently deployed indirect carrier modulation transmission systems(e.g. inductive coupled NFC and backscatter coupled RFID) suffer from afixed tradeoff between UL throughput, reliability and DL energyharvesting efficiency. Each specified device class is optimized foreither DL energy harvesting efficiency (i.e. battery-less passive classof devices) or UL throughput and reliability (i.e. semi-passive class ofdevices with on-board battery). Existing products are designed tosupport only a single class of operation and all classes supportrelatively low data rates.

Inductively Coupled Indirect Carrier Modulation Transmission

There is an inherent tradeoff between communication range and throughputin inductively coupled indirect carrier modulation transmission systems(e.g. NFC). Increasing the UL throughput by reducing the data symbolduration reduces the communication range.

A higher coupling quality factor between the reader and the transponderresults in a reduced bandwidth link. While this limits the realizableminimum duration of the UL data symbol and therefore maximum ULthroughput, it results in an increase in the DL power transferefficiency. Reducing the coupling quality factor in order to increasethe link bandwidth and thereby enable a shorter symbol duration tosupport a higher UL throughput reduces the DL power transfer efficiency.The reader and transponder must then be closer to each other in order tosupport fully passive or even semi-passive operation.

This tradeoff between UL communication range and throughput can bemitigated by using higher-order modulation (e.g. QPSK, 16-QAM). However,enabling higher-order modulation using conventional approaches intransmission systems that employ indirect carrier modulation suffersfrom a tradeoff between throughput and transponder complexity.

Currently proposed approaches map points from the UL constellation toindividual reflectance states in the antenna load modulator. This meansthat e.g. 16 different reflectance states are needed to support 16-QAM.Since the number of reflectance states scales with the modulation order,the complexity of the antenna load modulator can become impractical,especially for passive and semi-passive transponders supporting higherorder modulation (e.g. 64-QAM). Attention must be paid to passive andsemi-passive transponder complexity as it directly impacts cost of thetransponder.

Backscatter Coupled Indirect Carrier Modulation Transmission

In backscatter coupled indirect carrier modulation systems, there is aninherent tradeoff between reflected power on the UL and the harvestedpower on the DL. Performance of the UL is coupled to the DL via energyharvesting functionality in backscatter systems (e.g. RFID) thatsimultaneously exchange data on the UL while at the same time deliveringpower on the DL.

The choice of UL constellation (number and separation betweenconstellation points) impacts both the UL performance (e.g. throughput,BER) and the DL power harvesting efficiency. Improving ULsignal-to-noise ratio and therefore BER by creating wider separationbetween constellation points results in a reduction in the DL powerharvesting efficiency. Increasing UL throughput and spectral efficiencyusing higher order modulation for a specified minimum BER performancealso results in a reduction in the DL power harvesting efficiency.

Many emerging ultra-low power use cases envisioned for e.g. 5G NR areexpected to employ backscatter coupled indirect carrier modulationtransmission in the terminal device. These devices will have to supportmultiple modes of operation delivering increased data rates and linkreliability or long battery life, as needed. Such terminal devices couldbenefit from improved coded modulation schemes and constellationadaptation procedures for inductive and backscatter coupled indirectcarrier modulation transmission systems.

Constellation Adaptation

In indirect carrier modulation (ICM) transmission systems, theperformance of the UL is coupled to the DL via the energy harvestingfunctionality. For example, backscattering transponders (e.g. RFID)transmit data on the UL while at the same time harvesting energy on theDL using the same RF carrier. Two commonly used 1st order indirectcarrier modulation schemes and the associated 2-point constellations areillustrated in FIG. 2A and 2B, respectively. The constellation in FIG.2A utilizes On-off keying (OOK) with the zero-reflectance (100%absorbance) state, S0, of the ICM as a point in the constellation and azero-absorbance (100% reflectance) state, S1, whereas the constellationin FIG. 2B utilizes Binary Phase-Shift Keying (BPSK) with twozero-absorbance (100% reflectance) states, S1 and S2. The DL energyharvesting efficiency of the approach in FIG. 2B is 0% but it transmitsa higher energy per symbol in the UL as compared to the approach in FIG.2A. On the other hand, the approach in FIG. 2A delivers better DL energyharvesting efficiency but transmits lower energy per symbol in the UL.

Two examples of second order indirect carrier modulation schemes and theassociated 4-point constellations are illustrated in FIGS. 3A and 3B,respectively. The constellation in FIG. 3A utilizes QuadraturePhase-Shift Keying (QPSK) with four states, S1-S4, while theconstellation in FIG. 3B utilizes four-point Quadrature AmplitudeModulation (4-QAM) with the zero-reflectance (100% absorbance) state,S0, of the ICM as a point in the constellation. If the vector distance rof the return loss circle across constellation points is held constant,the scheme in FIG. 3A can transmit higher energy per bit and ensure arelatively higher minimum separation between constellation points,whereas the scheme in FIG. 3B can deliver better DL energy harvestingefficiency, but with a relatively lower minimum separation betweenconstellation points.

In an embodiment of the present principles, a WTRU can use an adaptivemethod in which the arrangement of constellation points for a givenmodulation order can be selected.

In such an adaptive method, the WTRU can adapt the signal constellationfor a specified uplink modulation order. By utilizing thezero-reflectance state of the ICM as a point in the UL signalconstellation (i.e. transmission muting), the UE can meet DL powerreception requirements. The UE can enhance UL reliability by increasingthe radii of return loss circles containing the ICM reflectance statesrepresenting points in the UL signal constellation. The WTRU can alsoperform signal constellation adaptation based on combined requirementsof energy harvesting, payload reliability requirements for ULtransmissions, and also select uplink signal constellation arrangementbased on for example at least one of current battery level indicator,downlink power reception efficiency and uplink payload reliability.

The tradeoff between energy harvesting and UL-reliability can beachieved by determining the arrangement of constellation points for acorresponding modulation order (i.e. a specific number of constellationpoints). The device can perform automatic constellation adaptationtriggered by e.g. a data re-transmission request from the network aswill be described.

FIG. 14 illustrates an example of a possible transmission method 1400according to an embodiment of the present principles. In the example, anetwork 1402 and a WTRU 1404 communicate.

In step S1401, the network sends an unmodulated (CW) transmission to theWTRU that reflects to the network a capability report, for exampleincluding a list of supported constellation arrangements for eachsupported modulation order.

In step S1403, the network sends to the WTRU a modulated transmissionincluding a WTRU Configuration with a priority order for at least partof the list of supported constellation arrangements.

In step S1405, the network sends an unmodulated (CW) transmission to theWTRU that uses the highest priority constellation arrangement for therelevant modulation order when reflecting data.

In step S1407, the network sends to the WTRU a modulated transmissionincluding a first retransmission request.

In step S1409, the network sends an unmodulated (CW) transmission to theWTRU that uses the next (i.e. second) highest priority constellationarrangement for the relevant modulation order when reflecting the datain the retransmission.

In step S1411, the network sends to the WTRU a modulated transmissionincluding a second retransmission request.

In step S1413, the network sends an unmodulated (CW) transmission to theWTRU that uses the next (i.e. third) highest priority constellationarrangement for the relevant modulation order when reflecting the datain the retransmission.

In an embodiment, the device can utilize a pre-specified orpre-configured modulation type and order with a pre-specified orpre-configured arrangement of points in the constellation to report itslist of supported constellation arrangements for each supportedmodulation order. As an example, the device can use the standardconstellation for OOK modulation illustrated in FIG. 2A to report itslist of supported constellation arrangements for each supportedmodulation. As an additional example, the list of constellationarrangements supported by the device for e.g. a second order modulationincluding the standard constellation for QPSK is illustrated in FIG. 3Aand a second constellation utilizing the zero-reflectance state (S0) isillustrated in FIG. 3B.

In another embodiment, the device receiving configuration including apriority order or ranking for the reported list of constellationarrangements for each reported modulation order. For example, a defaultconstellation type (e.g. highest priority) for e.g. battery-less passivedevices can be one that delivers highest supported DL energy harvestingefficiency; an example of a default constellation type for second ordermodulation is the constellation utilizing the zero-reflectance state(S0) illustrated in FIG. 3B. A lowest priority constellation for e.g.battery-less passive devices can be one that delivers the highest ULtransmitted energy per bit for a given modulation order; an example of alowest priority constellation type for second order modulation being thestandard constellation for QPSK illustrated in FIG. 3A.

In an embodiment, the device transmitting data uses the highest priorityconstellation arrangement delivering the highest supported DL energyharvesting efficiency.

In an embodiment, the device receives a data re-transmission requestfrom the network or fails to receive an ACK within a pre-specified timewindow for a consecutive specified, signaled or preconfigured number oftimes.

In an embodiment, upon receives a data re-transmission request from thenetwork, the device switches to the next configured constellation andmodulation type on the priority list to re-transmit the data.

In an embodiment, the device continues data transmission using theselected constellation and modulation type as long as no additional datare-transmission requests are received from the network. Otherwise, thedevice selects the next configured constellation and modulation types onthe priority list to re-transmit the data. The device can repeat thisprocess until the priority list is exhausted or an overall signaled orpreconfigured number of retransmissions has been achieved, upon whichthe device can declare a data transmission/connection failure.

Network assisted procedures where the WTRU has full control of whichconstellation arrangement for a given modulation order it uses will nowbe described in the following embodiments. In this case, the network isassumed to be capable of blindly detecting which transmissionconfiguration has been utilized for data transmission by the WTRU.

FIG. 15 illustrates an example of a possible transmission method 1500according to an embodiment of the present principles. In the example, anetwork 1502 and a WTRU 1504 communicate.

In step S1501, the network sends an unmodulated (CW) transmission to theWTRU that reflects to the network a capability report, for exampleincluding a list of supported constellation arrangements for eachsupported modulation order.

In step S1503, the network sends to the WTRU a modulated transmissionincluding a Channel-Quality Indicator (CQI) Mapping including a mappingbetween CQI values and supported constellation arrangements in thereported list.

In step S1505, the network sends to the WTRU a modulated transmissionincluding a CQI Measurement Assistance Configuration including unique IDand unique ID transmission occasions (e.g. timing and frequencyconfiguration). The unique ID is to be utilized for transmission by thedevice and allows the network to identify the transmitting device andmeasure the channel quality associated with the transmitting device.

In step S1507, the network sends an unmodulated (CW) transmission to theWTRU that reflects a Unique ID transmission to the network.

In step S1509, the network sends to the WTRU a modulated transmissionincluding a CQI Measurement Report.

In step S1511, the WTRU selects the constellation arrangement based onthe CQI value reported by the network and the configured CQI Mapping.

In step S1513, the network sends an unmodulated (CW) transmission to theWTRU that uses the selected constellation arrangement to reflect data tothe network.

In an embodiment, the WTRU utilizes a pre-specified or pre-configuredmodulation type and order with a pre-specified or pre-configuredarrangement of points in the constellation to report its list ofsupported constellation arrangements for each supported modulationorder. As an example, the WTRU can use the standard constellation forOOK modulation illustrated in FIG. 2A to report its list of supportedconstellation arrangements for each supported modulation. As anadditional example, the list of constellation arrangements supported bythe WTRU for e.g. a second order modulation includes the standardconstellation for QPSK illustrated in FIG. 3A and a second constellationutilizing the zero-reflectance state (S0) illustrated in FIG. 3B.

In an embodiment, the WTRU receives a mapping between Channel-QualityIndicator (CQI) values and the reported list of constellationarrangements for each reported modulation order.

In an embodiment, the WTRU receives CQI measurement assistanceconfiguration, e.g. a unique ID, periodicity of the unique IDtransmission occasions.

In an embodiment, the WTRU utilizes signaled modulation type/order andconstellation/symbol configuration to periodically transmit theconfigured unique ID and facilitate CQI measurement by the network.

In an embodiment, the WTRU receives a CQI measurement report includingthe current measured CQI value (Q_(i)) from the network periodically orconditional on Q_(i) satisfying the relationship|Q_(i)−f({Q_(j)}_(j∈{i−N,i−N+1, . . . i−1)})|>δ where f ( ) is afunction of the last N measurements.

In an embodiment, the WTRU selects the constellation arrangement fromthe pre-configured list based on the CQI value reported by the networkand preconfigured mapping.

In an embodiment, the WTRU continues data transmission using theselected new constellation arrangement and modulation order.

A fully autonomous procedure where a WTRU performs constellationadaptation based on the evaluation of a performance indicator isdescribed in the following embodiments.

FIG. 16 illustrates an example of a possible transmission method 1600according to an embodiment of the present principles. In the example, anetwork 1602 and a WTRU 1604 communicate and it is assumed that thenetwork is capable of blindly detecting which transmission configurationhas been utilized for data transmission by the WTRU.

In step S1601, the network sends an unmodulated (CW) transmission to theWTRU that reflects to the network a capability report, for exampleincluding a list of supported constellation arrangements for eachsupported modulation order.

In step S1603, the network sends to the WTRU a modulated transmissionincluding a Received Interrogation Signal Strength (RISS) MeasurementAssistance Configuration message including CW transmission occasions toallow RISS measurement.

In step S1605, the network sends an unmodulated (CW) transmission to theWTRU that reflects data to the network.

In step S1607, the network sends to the WTRU an unmodulatedtransmission, as announced in the RISS Measurement AssistanceConfiguration message.

In step S1609, the WTRU measures its DL energy harvesting efficiency η.

In step S1611, the network sends to the WTRU a modulated transmissionincluding a retransmission request.

In step S1613, the WTRU selects a new constellation arrangement based onperformance indicators, e.g. {ηRISS−P_(ICM)}(N/R)>δ and E_(TX)>Δ, wherePicts is the power consumption of the ICM when configured for the newconstellation, N is the UL data packet size, R the UL data rate, E_(TX)in the UL transmitted energy per symbol and δ, Δ are optimization goalsthat might be preconfigured at the UE or signaled by the network as partof triggering criteria.

In step S1615, the network sends an unmodulated (CW) transmission to theWTRU that uses a pre-configured or pre-specified modulation type toreflect to the network a Transmission Adaptation Notification.

In step S1617, the network sends an unmodulated (CW) transmission to theWTRU that uses the newly selected constellation arrangement to reflectdata to the network.

In an embodiment, the WTRU utilizes a pre-specified or pre-configuredmodulation type and order with a pre-specified or pre-configuredarrangement of points in the constellation to report its list ofsupported constellation arrangements for each supported modulationorder. As an example, the WTRU uses the standard constellation for OOKmodulation illustrated in FIG. 2A to report its list of supportedconstellation arrangements for each supported modulation. As a furtherexample, the list of constellation arrangements supported by the devicefor e.g. a second order modulation includes the standard constellationfor QPSK illustrated in FIG. 3A and a second constellation utilizing thezero-reflectance state (S0) illustrated in FIG. 3B.

In an embodiment, the WTRU receives configuration of occasions formeasuring the received interrogation signal strength (RISS).

In an embodiment, the WTRU receives CW transmissions from the networkand measures RISS over one or more measurement occasions and determinesthe DL energy harvesting efficiency (η) associated with current ULtransmission configuration.

In an embodiment, the WTRU receives a data re-transmission request fromthe network or a notification from its PMU.

In an embodiment, the WTRU selects a new constellation arrangement fromthe list of pre-specified UL constellation arrangements such that theperformance indicators (E_(H)−F_(RX))={ηRISS−P_(ICM)}(N/R)>δ andE_(TX)>Δ, where P_(ICM) is the power consumption of the ICM whenconfigured for the new constellation, N is the UL data packet size, Rthe UL data rate, E_(TX) is the UL transmitted energy per symbol and δ,Δ are optimization goals that might be preconfigured at the WTRU orsignaled by the network as part of triggering criteria.

In an embodiment, the WTRU utilizes a pre-specified/pre-configuredmodulation type and order with a pre-specified/pre-configuredarrangement of points in the constellation to transmit a UL transmissionadaptation notification message indicating the newly selectedtransmission configuration to be used in the following UL data packets.This embodiment may be omitted in the set of steps taken by the WTRU asillustrated in FIG. 15 if the network is assumed to be capable ofblindly detecting which transmission configuration has been utilized fordata transmission by the WTRU.

In an embodiment, the WTRU transmits UL data packets using the newtransmission configuration including a new constellation arrangement.

Hybrid Phase-Amplitude Indirect Carrier Modulation

In indirect carrier modulation transmission systems, the performance ofthe UL is coupled to the DL via energy harvesting functionality. Forexample, backscattering transponders (e.g. RFID) transmit data on the ULwhile at the same time harvesting energy on the DL using the same RFcarrier. The ICM state transitions and the transmitted waveformassociated with a commonly used Manchester-encoded on-off keying (OOK)indirect carrier modulation scheme is illustrated in FIGS. 4A and 4B.The illustrated scheme is used to transmit one bit per symbol. Thescheme employs a 50% duty cycle factor and splits the symbol period intotwo equal sections. When transmitting a ‘0’, the ICM is remains inreflectance state S1 during the first half of the symbol and transitionsto zero-reflectance state S0 in the second half of the symbol. The ICMstate transitions are reversed when transmitting a ‘1’ as illustrated inthe right-hand side of.

The DL energy harvesting efficiency is defined as the portion of theincident RF energy that is harvested and stored in the transponder'sbattery. The normalized energy harvesting efficiency of the DL isη=E_(H)/E₀, where E₀ is the available incident energy and E_(H) is theharvested energy. The harvested energy E_(H) is defined as

E _(H)=(T/2)P _(IN)Σ_(k=0) ¹(1−Γ_(k))   (Equation 1)

T is the symbol duration and Γ_(k) are the power reflectancecoefficients associated with the ICM state used to represent eachsymbol. Note that for the example illustrated in FIG. 4A, Γ=0 for S0 andΓ=1 for S1 and E_(H)=TP_(IN)/2. E₀ is computed assuming that the ICMremains in state S0 (Γ=0) for the entire duration T and thereforeE₀=TP_(IN) and the normalized energy harvesting efficiency η=50%. Asimilar approach can be used to determine the transmitted energy persymbol E_(TX) as defined as

E _(TX)=(T/2)P _(IN)Σ_(k=0) ¹Γ_(k)   (Equation 1)

For the example illustrated in FIG. 4A, Γ=0 for S0 and Γ=1 for S1 andE_(TX)=TP_(IN)/2. The gNB receiver-decoder uses a data slicer includinga carrier threshold detector. Since the bit duration and the duty cyclefactor are specified by standards, the gNB receiver-decoder knows whereto sample the received waveform.

FIGS. 5A and 5B illustrate another example of a Manchester-encodedindirect carrier modulation scheme employing binary phase-shift-keying(BPSK) to transmit one bit per symbol. The scheme employs a 50% dutycycle factor and splits the symbol period into two equal sections. Whentransmitting a ‘0’, the ICM is in state S1 during the first half of thesymbol and transitions to state S2 in the second half of the symbol. TheICM state transitions are reversed when transmitting a ‘1’ asillustrated in FIGS. 5A and 5B. it is noted that for the exampleillustrated in FIG. 5A, Γ=1 for both S1 for S2. Thus, the harvestedenergy E_(H)=0, the normalized energy harvesting efficiency η=0 and,since all the incident RF energy is reflected, and thereforeE_(TX)=TP_(IN). The gNB receiver-decoder uses a phase discriminator.Since the bit duration and the duty cycle factor are specified bystandards, the gNB receiver-decoder knows where to look for the phasetransitions in the received waveform.

In comparison, the coded indirect carrier modulation scheme illustratedin Error! Reference source not found., employing OOK, provides a betterenergy harvesting efficiency while the scheme illustrated in Error!Reference source not found, employing BPSK, delivers a highertransmitted energy per bit. This represents a fixed tradeoff between DLenergy harvesting efficiency and UL reliability. As can be seen,flexible coded modulation schemes that can provide additional degrees offreedom such that a tradeoff between DL energy harvesting and ULreliability can be made as required by different use cases anddeployment scenarios can be desired.

FIGS. 6A and 6B illustrate a hybrid phase-amplitude indirect carriermodulation scheme according to an embodiment of the present principles.The example scheme is for transmitting one bit per symbol.

Generally speaking, such a hybrid phase-amplitude indirect carriermodulation scheme can be obtained by a UE using hybrid phase-amplitudeindirect RF carrier modulation with two degrees of freedom for encodeddata transmission, wherein the two degrees of freedom can be a dutycycle factor and a modulation depth. The UE can use changes in carrieramplitude and carrier phase to encode data symbols and symbolboundaries. The ICM states can be arranged into two pairs of antipodalreflectance states {S1, S2} and {S3, S4}, and a first symbol can beencoded using a duty cycle factor and a transition from state S4 to S1,while a second can be encoded using a duty cycle factor and a transitionfrom state S2 to S3.

As mentioned, one of the degrees of freedom is the duty cycle factor ξthat can be configured, where 0<ξ<1. This means that the data symbol issplit into two portions, ξT and (1−ξ)T. The ICM remains in state S4during the first ξT portion of the symbol and transitions to state S1for the remaining (1−ξ)T portion of the symbol when transmitting a ‘0’.The ICM remains in state S2 during the first (1−ξ)T portion of thesymbol and transitions to state S3 during the remaining ξT portion ofthe symbol when transmitting a ‘1’. It will be understood, that thesignificance of the state transitions can be different, for exampleinversed.

States S1, S2 can implement the same power reflectance coefficientΓ_(1,2) and the states S3, S4 can implement the same power reflectancecoefficient Γ_(3,4). It is noted that there is a 180-degree phasedifference in the reflected waveforms associated with states S1 and S2and that, similarly, there is a 180-degree phase difference in thereflected waveforms associated with states S3 and S4. The modulationdepth 6 is defined as the ratio of the two power reflectancecoefficients Γ_(1,2) and Γ_(3,4,) specifically δ=Γ_(1,2)/Γ_(3,4).

The normalized energy harvesting efficiency of the DL is η=E_(H)/E₀where E₀=TP_(IN) is the available incident energy and E_(H) is theharvested energy. The harvested energy E_(H) is

E _(H) =TP _(IN){ξ(1−Γ_(3,4))+(1−ξ)(1−Γ_(1,2))}  (Equation 2)

where T is the symbol duration and Γ_(1,2) and Γ_(3,4) are the powerreflectance coefficients associated with the ICM state used to representeach symbol. It is noted that for the example illustrated in FIG. 6A,Γ_(3,4)=1. Assuming that Γ_(1,2)=½ and ξ=0.25 the harvested energy

$E_{H} = {\frac{3}{8}{{TP}_{IN}.}}$

Therefore, the normalized energy harvesting efficiency η=37.5%. Asimilar approach can be used to determine the transmitted energy persymbol E_(TX) as

E _(TX) =TP _(IN){ξΓ_(3,4)+(1−ξ)Γ_(1,2)}  (Equation 3)

For the example illustrated in FIG. 6A, assuming that Γ_(1,2)=½ andξ=0.25 the transmitted energy per symbol

$E_{TX} = {\frac{5}{8}T{P_{IN}.}}$

The duty cycle factor ξ and the modulation depth δ based on ULtransmission reliability and power harvesting requirements can beselected as follows.

The DL energy harvesting efficiency can be increased by reducing theduty cycle factor and increasing the modulation depth.

The UL reliability (i.e. transmitted energy per bit) can be increased byincreasing the duty cycle factor and reducing the modulation depth.

FIGS. 7A and 7B illustrate a decoding scheme for hybrid phase-amplitudeindirect carrier modulation transmission according to an embodiment ofthe present principles. FIG. 7A illustrates the transmitted waveform,similar to that in FIG. 6B, and FIG. 7B illustrates output waveforms ofa receiver-decoder employing an amplitude and a phase detector.

The WTRU can use a data slicer (e.g. amplitude detector) including acarrier threshold detector and a phase detector to detect the boundariesbetween the data symbols and the boundaries within the symbol. Theallowable settings for the duty cycle factor ξ and the modulation depthb can be specified by standards so that the UE knows how to set the dataslicer threshold and where to sample the output of the data slicer.

The tradeoff between energy harvesting and UL-reliability can beachieved by determining the appropriate combination of values for theparameter pair {ξ, δ} describing the modulation scheme and including theduty cycle factor ξ and the modulation depth δ. The WTRU can performautomatic constellation adaptation triggered by e.g. a datare-transmission request from the network using the embodiments below.

FIG. 17 illustrates an example of a possible transmission method 1700according to an embodiment of the present principles. In the example, anetwork 1702 and a WTRU 1704 communicate.

In step S1701, the network sends an unmodulated (CW) transmission to theWTRU that reflects to the network a capability report, for exampleincluding a list of supported duty cycle factors ξ and modulation depthsδ.

In step S1703, the network sends to the WTRU a modulated transmissionincluding a WTRU Configuration with a priority order for at least partof the list of supported values for the parameter pair {ξ,δ}.

In step S1705, the network sends an unmodulated (CW) transmission to theWTRU that uses the highest priority settings for the parameter pair{ξ,δ} when reflecting data.

In step S1707, the network sends to the WTRU a modulated transmissionincluding a first retransmission request.

In step S1709, the network sends an unmodulated (CW) transmission to theWTRU that uses the next (i.e. second) highest priority settings for theparameter pair {ξ,δ} when reflecting the data in the retransmission.

In step S1711, the network sends to the WTRU a modulated transmissionincluding a second retransmission request.

In step S1713, the network sends an unmodulated (CW) transmission to theWTRU that uses the next (i.e. third) highest priority settings for theparameter pair {ξ,δ} when reflecting the data in the retransmission.

In an embodiment, the WTRU utilizes a pre-specified/pre-configuredmodulation type to report its list of supported duty cycle factors ξ andthe modulation depths δ for hybrid phase-amplitude indirect carriermodulation.

In an embodiment, the WTRU receives a priority order or ranking for thereported list of supported values for the parameter pair {ξ, δ} where,for example, a default (highest priority) set of values for theparameter pair {ξ, δ} for e.g. passive devices is one that delivershighest supported DL energy harvesting efficiency; for instance, thedefault (highest priority) values for the parameter pair {ξ, δ} is thelowest supported duty cycle factor and the highest supported modulationdepth to optimize DL energy harvesting. A lowest priority set of valuesfor the parameter pair {ξ, δ} for e.g. passive devices is one thatdelivers the highest UL transmitted energy per bit; for instance, thelowest priority values for the parameter pair {ξ, δ} is the highestsupported duty cycle factor and the lowest supported the modulationdepth to optimize UL reliability (transmitted energy per bit).

In an embodiment, the WTRU commences data transmission using the default(highest priority) settings for the parameter pair {ξ, δ}.

In an embodiment, the WTRU receives data re-transmission request orfailing to receive an ACK within a pre-specified time window for aconsecutive specified, signaled, or preconfigured number of times.

In an embodiment, the WTRU switches to the next configured settings forthe parameter pair {ξ, δ} on the priority list to re-transmit the data.

In an embodiment, the WTRU continues data transmission using theselected new settings for the parameter pair {ξ, δ} as long as noadditional data re-transmission requests are received from the network.Otherwise, the device selects the next configured values for theparameter pair {ξ, δ} on the priority list to re-transmit the data. TheWTRU continues this process until the priority list is exhausted or anoverall signaled or preconfigured number of retransmissions is achieved,after which the WTRU declares a data transmission/connection failure.

Network assisted procedures where the WTRU has full control of whichvalues for the parameter pair {ξ, δ} it uses is described in thefollowing embodiments. In this case, the network is assumed to becapable of blindly detecting which transmission configuration has beenutilized for data transmission by the WTRU.

FIG. 18 illustrates an example of a possible transmission method 1800according to an embodiment of the present principles. In the example, anetwork 1802 and a WTRU 1804 communicate.

In step S1801, the network sends an unmodulated (CW) transmission to theWTRU that reflects to the network a capability report, for exampleincluding a list of supported duty cycle factors ξ and modulation depthsδ.

In step S1803, the network sends to the WTRU a modulated transmissionincluding a Channel-Quality Indicator (CQI) Mapping including a mappingbetween CQI values and at least part of the list of supported values forthe parameter pair {ξ,δ}.

In step S1805, the network sends to the WTRU a modulated transmissionincluding a CQI Measurement Assistance Configuration including unique IDand unique ID transmission occasions (e.g. timing and frequencyconfiguration). The unique ID is to be utilized for transmission by thedevice and allows the network to identify the transmitting device andmeasure the channel quality associated with the transmitting device.

In step S1807, the network sends an unmodulated (CW) transmission to theWTRU that reflects a Unique ID transmission to the network.

In step S1809, the network sends to the WTRU a modulated transmissionincluding a CQI Measurement Report.

In step S1811, the WTRU selects the parameter pair {ξ,δ} based on theCQI value reported by the network and the configured CQI Mapping.

In step S1813, the network sends an unmodulated (CW) transmission to theWTRU that uses the selected parameter pair {ξ,δ} to reflect data to thenetwork.

In an embodiment, the WTRU utilizes a pre-specified/pre-configuredmodulation type to report its list of supported duty cycle factors ξ andthe modulation depths δ for hybrid phase-amplitude indirect carriermodulation.

In an embodiment, the WTRU receives a mapping between CQI values and thereported list of values for the parameter pair {ξ, δ}.

In an embodiment, the WTRU receives CQI measurement assistanceconfiguration, e.g. a unique ID, periodicity of the unique IDtransmission occasions.

In an embodiment, the WTRU utilizes signaled modulation type/order andconstellation/symbol configuration to periodically transmit theconfigured unique ID and facilitate CQI measurement by the network.

In an embodiment, the WTRU receives a CQI measurement report includingthe current measured CQI value (Q₁) from the network periodically orconditional on Q_(i) satisfying the following relationship|Q_(i)−f({Q_(j)}_(j∈{i−N,i−N+1, . . . i−1}))|>δ where f ( ) is afunction of the last N measurements.

In an embodiment, the WTRU selects the values for the parameter pair {ξ,δ} from the list reported in the first embodiment based on the CQI valuereported by the network and a received preconfigured mapping between CQIvalues and the reported list of values for the parameter pair {ξ, δ}.

In an embodiment, the WTRU continues data transmission using theselected new values for the parameter pair {ξ, δ}.

A fully autonomous procedure where a WTRU performs constellationadaptation based on the evaluation of a performance indicator isdescribed in the following embodiments.

FIG. 19 illustrates an example of a possible transmission method 1900according to an embodiment of the present principles. In the example, anetwork 1902 and a WTRU 1904 communicate and it is assumed that thenetwork is capable of blindly detecting which transmission configurationhas been utilized for data transmission by the WTRU.

In step S1901, the network sends an unmodulated (CW) transmission to theWTRU that reflects to the network a capability report, for exampleincluding a list of supported duty cycle factors ξ and modulation depthsδ.

In step S1903, the network sends to the WTRU a modulated transmissionincluding a Received Interrogation Signal Strength (RISS) MeasurementAssistance Configuration message including CW transmission occasions toallow RISS measurement.

In step S1905, the network sends an unmodulated (CW) transmission to theWTRU that reflects data to the network.

In step S1907, the network sends to the WTRU an unmodulatedtransmission, as announced in the RISS Measurement AssistanceConfiguration message.

In step S1909, the WTRU measures its DL energy harvesting efficiency η.

In step S1911, the network sends to the WTRU a modulated transmissionincluding a retransmission request.

In step S1913, the WTRU selects a new constellation arrangement based onperformance indicators, e.g. {ηRISS−P_(ICM)}(N/R)>δ and E_(TX)>Δ, whereP_(ICM) is the power consumption of the ICM when configured for the newconstellation, N is the UL data packet size, R the UL data rate, E_(TX)is the UL transmitted energy per symbol and δ, Δ are optimization goalsthat might be preconfigured at the UE or signaled by the network as partof triggering criteria.

In step S1915, the network sends an unmodulated (CW) transmission to theWTRU that uses a pre-configured or pre-specified modulation type toreflect to the network a Transmission Adaptation Notification.

In step S1917, the network sends an unmodulated (CW) transmission to theWTRU that uses the newly selected constellation arrangement to reflectdata to the network.

In an embodiment, the WTRU utilizes a pre-specified/pre-configuredmodulation type to report its list of supported duty cycle factors ξ andthe modulation depths δ for hybrid phase-amplitude indirect carriermodulation.

In an embodiment, the WTRU receives configuration of occasions formeasuring the Received Interrogation Signal Strength (RISS).

In an embodiment, the WTRU receives CW transmissions from the networkand measuring RISS over one or more measurement occasions and determinesthe DL energy harvesting efficiency (η) associated with current ULtransmission configuration.

In an embodiment, the WTRU receives a data re-transmission request fromthe network or a notification from its PMU.

In an embodiment, the WTRU selects new values for the parameter pair {ξ,δ} from the list reported in the first embodiment such that theperformance indicators (E_(H)−E_(TX))={ηRISS−P_(ICM)}(N/R)>δ and E_(TX)Δwhere P_(ICM) is the power consumption of the ICM when configured forthe new constellation, N is the UL data packet size, R the UL data rate,E_(TX) is the UL transmitted energy per symbol and δ, Δ are optimizationgoals that might be preconfigured at the UE or signaled by the networkas part of triggering criteria.

In an embodiment, the WTRU utilizes a pre-specified/pre-configuredmodulation type and order with a pre-specified/pre-configuredarrangement of points in the constellation to transmit a transmissionadaptation notification message indicating the newly selectedtransmission configuration to be used in the following UL data packets.This embodiment may be omitted in the set of steps taken by the WTRUillustrated in FIG. 19 if the network is assumed to be capable ofblindly detecting which transmission configuration has been utilized fordata transmission by the UE.

In an embodiment, the WTRU transmits UL data packets using the newtransmission configuration including the new set of values for theparameter pair {ξ, δ}.

Sparse Block Code Based Indirect Carrier Modulation

In ICM transmission systems, the performance of the UL is coupled to theDL via energy harvesting functionality. For example, backscatteringtransponders (e.g. RFID) transmit data on the UL while at the same timeharvesting energy on the DL using the same RF carrier. The use of sparseblock codes for the UL can improve the DL energy harvesting efficiencyif transmission muting is used to represent the ‘0’ entries of the code.

FIGS. 8A-8C illustrate an example of a sparse block code, FIG. 8A, andthe associated carrier modulation scheme, where n bits of data arepacked into each symbol and each symbol is represented by a sequence ofN=2^(n) code bits. In FIG. 8A, n=2 and N=4. The code representing eachdata symbol contains only one non-zero entry.

A general description of the ICM state transitions associated with thecode sequences is illustrated in FIG. 8B. The ‘0’ entries in the codeare represented by configuring the ICM to state S0. The load attached tothe antenna can be configured to match the antenna impedance (e.g. 50Ohm) when the ICM is configured to state S0 as shown in FIG. 8B. The RFcarrier can be fully absorbed when the ICM is in state S0. Therefore,during the transmission of the ‘0’ entries in the code, all or most ofthe incident RF energy can be absorbed, which can result in maximum DLenergy harvesting efficiency, referred to as transmission muting. TheICM transitions from e.g. state S0 to S1 when transmitting the ‘1’ entryin the code. State S1 in FIG. 8B represents a short circuit and,therefore, the incident RF energy is reflected. Thus, during thetransmission of the ‘1’ entries in the code, all of the incident RFenergy can be reflected, resulting in maximum transmitted energy.

FIG. 8C illustrates a time domain description of the transmittedwaveforms corresponding to each of the {n=2, N=4} sparse block codes.The DL energy harvesting efficiency is defined as the portion of theincident RF energy that is harvested and stored in the transponder'sbattery. The normalized energy harvesting efficiency of the DL isη=E_(H)/E₀ where E₀ is the available incident energy and E_(H) is theharvested energy. The harvested energy E_(H) is

E _(H) =T _(C) P _(IN)Σ_(k=0) ^(N−1)(1−Γ_(k))   (Equation 5)

where T_(C) is the time duration of each element in the sparse blockcode and Γ_(k) are the power reflectance coefficients associated withthe ICM state used to represent each code entry. It is noted that forthe example illustrated in FIG. 8B, Γ=0 for S0 and Γ=1 for S1 andE_(H)=3T_(C)P_(IN). E₀ is computed assuming that the ICM remains isstate S0 (Γ=0) for all four of the code entries and thereforeE₀=4T_(C)P_(IN) and the normalized energy harvesting efficiency η=75%. Asimilar approach can be used to determine the transmitted energy persymbol ETX as

E _(TX) 32 T _(C) P _(IN) Σ_(k=0) ^(N−1)Γ_(k)   (Equation 6)

For the example illustrated in FIG. 8B, Γ=0 for S0 and Γ=1 for S1 andE_(TX)=T_(C)P_(IN).

Two alternative embodiments of a sparse block coding scheme areillustrated in FIGS. 20A and 20B. FIG. 20A illustrates a codeimplementing maximum sparsity (code rate=½) delivering DL energyharvesting efficiency η=75% and transmitted UL energy per symbolE_(TX)=T_(C)P_(IN). FIG. 20B illustrates a rate=⅖ sparse block codedelivering DL energy harvesting efficiency η=60% and transmitted ULenergy per symbol E_(TX)=(⅖) T_(C)P_(IN).

Flexible coding schemes can be needed for indirect carrier modulationtransmission that introduce multiple degrees of freedom such that atradeoff between DL energy harvesting and UL reliability can be made asrequired by different use cases and deployment scenarios. A generaldescription of how this tradeoff can be achieved using sparse blockcodes is outlined hereafter.

A device can increase the sparsity level or equivalently the rate of asparse block code to increase the DL energy harvesting efficiency.

Conversely, a device can reduce the sparsity level or equivalently therate of a sparse block code to increase the transmitted energy per ULsymbol and hence UL reliability.

The reliability of a UL employing sparse-block-code-based ICMtransmission can be improved by introducing additional degrees offreedom to the sparse block coding based indirect carrier modulationscheme. FIGS. 9A-9C illustrate sparse block code according to anembodiment of the present principles. FIG. 9A illustrates the codingscheme and FIG. 9 the ICM state transitions.

Generally speaking, according to the embodiment, a UE uses phasereversals in the RF carrier to represent non-zero entries in sparseblock codes and transmits the phase reversal in a data encoding sequenceusing transitions between a pair of antipodal reflectance states {S1,S2} in the ICM. The reliability of the transmission can be improved bymapping the antipodal reflectance states of the ICM to open and shortterminations of the antenna. The UE can use one of the reflectancestates from an antipodal pair to transmit a reference phase forphase-coherent indirect carrier modulated transmission, and can usedirectional transitions between a pair of antipodal reflectance states{S1, S2} to indicate phase reversal direction change.

The ‘0’ entries in the code can be represented by configuring the ICM tostate S0. The ICM can transition from state S0 to S1 and then to S2 whentransmitting the ‘1’ entry in the code. State S1 in FIG. 9B canrepresent a short circuit and state S2 can represent an open circuit.Both states S1 and S2 can reflect all of the incident RF energy but thetransition from state S1 to S2 results in a carrier phase reversal. FIG.9C illustrates the time domain description of the transmitted waveformscorresponding to each of the {n=2, N=4} sparse block codes.

It is noted that for a first order the harvesting efficiency η and thetransmitted energy per symbol E^(TX) are the same for the two approachesdescribed in FIGS. 8A-8C and FIGS. 9A-9C. However, the transmissionscheme described in FIGS. 9A-9C can improve the reliability of the UL byintroducing an additional degree of freedom by the introduction of aphase reversal in the middle of the sinusoidal wave packet representingthe ‘1’ entry in the sparse block code. The UE can then use a decoderthat employs both an amplitude and phase detector. The power consumptionof the load modulator in the UE's transponder is expected to increasesince it executes 3 state transitions in the antenna load instead of 2while transmitting the ‘1’ entry in the sparse block code, which canslightly reduce the overall energy-efficiency of the of the UE.

Dense Block Code Based Indirect Carrier Modulation

In indirect carrier modulation transmission systems, the performance ofthe UL is coupled to the DL via energy harvesting functionality. Forexample, backscattering transponders (e.g. RFID) transmit data on the ULwhile at the same time harvesting energy on the DL using the same RFcarrier. Using dense block codes where a perfect-reflectance state (e.g.S1 in FIG. 21B illustrating ICM state transitions) is used to representthe ‘1’ entries of the dense block code can improve the UL reliabilityby increasing the transmitted energy per symbol. An example of a denseblock code and the associated carrier modulation scheme is illustratedin FIGS. 21A and 21B where n bits of data are packed into each symboland each symbol is represented by a sequence of N=2n code bits. In FIG.21A, n=2 and N=4. The code representing each data symbol contains onlyone zero entry.

A general description of the ICM state transitions associated with thecode sequences is illustrated in FIG. 21B. The ‘0’ entries in the codeare represented by configuring the ICM to state S0. The load attached tothe antenna is configured to match the antenna impedance (e.g. 50 Ohm)when the ICM is configured to state S0 as shown in Error! Referencesource not found. (b). The RF carrier is fully absorbed when the ICM isin state S0. Therefore, during the transmission of the ‘0’ entries inthe code, all or most of the incident RF energy is absorbed. The ICMtransitions from e.g. state S0 to S1 when transmitting the ‘1’ entry inthe code. State S1 in FIG. 21B represents a short circuit and therefore,all of the incident RF energy is reflected. Therefore, during thetransmission of the ‘1’ entries in the code, all of the incident RFenergy is reflected resulting in maximum transmitted energy.

Time domain description of the transmitted waveforms corresponding toeach of the {n=2, N=4} dense block codes are illustrated in FIG. 22 .The DL energy harvesting efficiency is defined as the portion of theincident RF energy that is harvested and stored in the transponder'sbattery. The normalized energy harvesting efficiency of the DL isη=E_(H)/E₀ where E₀ is the available incident energy and E_(H) is theharvested energy. The harvested energy E_(H) is defined as

E _(H) =T _(C) P _(IN)Σ_(k=0) ^(N−1)(1−Γ_(k))   (Equation 7)

T_(C) is the time duration of each element in the dense block code andΓ_(k) are the power reflectance coefficients associated with the ICMstate used to represent each code entry. For the example illustrated inFIG. 21B, Γ=0 for S₀ and Γ=1 for S₁ and E_(H)=T_(C)P_(IN). E₀ iscomputed assuming that the ICM remains is state S₀ (Γ=0) for all four ofthe code entries and therefore E₀=4T_(C)P_(IN) and the normalized energyharvesting efficiency η=25%. A similar approach can be used to determinethe transmitted energy per symbol E_(TX) as

E _(TX) =T _(C) P _(IN)Σ_(k=0) ^(N−1)Γ_(k)   (Equation 8)

For the example illustrated in FIG. 21B, Γ=0 for S₀ and Γ=1 for S₁ andE_(TX)=(¾)T_(C)P_(IN).

Two alternative embodiments of a dense block coding scheme areillustrated in FIGS. 23A and 23B. FIG. 23A illustrates a codeimplementing maximum density (code rate=½) delivering DL energyharvesting efficiency η=25% and transmitted UL energy per symbolE_(TX)=(¾)T_(C)P_(IN). FIG. 23B illustrates a rate=⅖ dense block codedelivering DL energy harvesting efficiency η=40% and transmitted ULenergy per symbol E_(TX)=(⅗)T_(C)P_(IN).

Flexible coding schemes can be needed for indirect carrier modulationtransmission that introduce multiple degrees of freedom such that atradeoff between DL energy harvesting and UL reliability can be made asrequired by different use cases and deployment scenarios. A generaldescription of how this tradeoff can be achieved using dense block codesis outlined hereafter.

A device can increase the density level or equivalently the rate of adense block code to increase the transmitted energy per UL symbol andhence UL reliability. Conversely, a device can reduce the density levelor equivalently the rate of a dense block code to increase the DL energyharvesting efficiency.

UE Procedures

As already explained, a UE can concurrently receive power and transmitinformation on the same RF carrier. The UE can act to enable concurrentefficient DL energy harvesting (EH) and reliable UL data transmission inICM transmission systems. The desired EH/UL-reliability tradeoff can beobtained by determining a constellation type (e.g. ICM, HybridPhase-Amplitude ICM, Sparse Block Code ICM, Dense Block Code ICM) for acorresponding modulation order (i.e. a specific number of constellationpoints) and selecting the constellation/symbol configuration thatoptimizes DL EH efficiency for a specified UL transmission reliability.This can, broadly speaking, be network-controlled or UE controlled.

In an embodiment of a method 1000 according to the present principles,illustrated in FIG. 10 , the UE can perform constellation adaptationafter a data re-transmission request from the network.

In step S1002, the UE utilizes a mandatory standardized modulationtype/order with specific constellation/symbol configuration to reportits supported class(es) or list of supported modulation type(s)/order(s)and corresponding constellation/symbol configuration to the network.

In step S1004, the UE receives a priority order or ranking for thereported list of modulation and constellation configuration (for eachmodulation order), wherein a default constellation type (i.e. withhighest priority) is one that delivers highest supported DL energyharvesting efficiency, and a lowest priority constellation is one thatdelivers the highest UL transmitted energy per bit for a givenmodulation order.

In step S1006, the UE transmits data using the highest priorityconstellation delivering the highest supported DL energy harvestingefficiency.

In step S1008, the UE receives a data re-transmission request or failsto receive an ACK within a pre-specified time window for a consecutivespecified signaled/preconfigured number of times.

In step S1010, the UE switches to the next configured constellation andmodulation type on the priority list to re-transmit the data.

In step S1012, the UE continues data transmission using the selectedconstellation and modulation type as long as it does not receive are-transmission request or receives ACKs, cf. step S1008. Otherwise, itrepeats step S1010 until the priority list is exhausted or an overallsignaled/preconfigured aggregate number of retransmissions is achieved,at which point the UE declares a data transmission/connection failure.

The default (i.e. highest priority) constellation configuration in stepS1004 can utilize the zero-reflectance state of the ICM as a point inthe UL signal constellation for efficient DL EH, can be a hybridphase-amplitude indirect carrier modulation scheme with the lowestsupported duty cycle factor and the highest supported modulation depthfor efficient DL EH, or can be a sparse block code based indirectcarrier modulation scheme with maximum number of supportedzero-reflectance states per code.

The lowest priority constellation in step S1004 can be a hybridphase-amplitude indirect carrier modulation scheme with the highestsupported duty cycle factor and the lowest supported modulation depth,or a sparse block code based indirect carrier modulation schemeincluding a phase reversal in the sinusoidal wave packet representingthe non-zero code entries.

In the method illustrated in FIG. 10 , the UE makes the decision onwhich modulation type/order and associated constellation configurationto be used based on assisting information from the network in the formof priority/ranking list.

FIG. 11 illustrates a method 1100 according to an embodiment of thepresent principles in which the UE has full control of which modulationtype/order and constellation configuration to be used without anyassisting information from the network. It is assumed that the networkis capable of blindly detecting which transmission configuration hasbeen utilized for data transmission by the UE. In this embodiment, theUE can perform constellation adaptation based on Channel-QualityIndicator (CQI) measurements reported by the network.

In step S1102, the UE utilizes a mandatory standardized modulationtype/order with specific constellation/symbol configuration to reportits supported class(es) or list of supported modulation type(s)/order(s)and corresponding receiving constellation/symbol configuration for eachsupported modulation type.

In step S1104, the UE receives a mapping between CQI values andmodulation type(s)/order(s) and corresponding constellation/symbolconfiguration based on the reported values.

In step S1106, the UE receives CQI measurement assistance configuration,e.g. a unique ID, periodicity of the unique ID transmission occasions,and modulation type/order and constellation/symbol configuration.

In step S1108, the UE utilizes the signaled modulation type/order andconstellation/symbol configuration to transmit, e.g. periodically, theconfigured unique ID and facilitates CQI measurement by the network.

In step S1110, the UE receives a current measured CQI value (Q_(i)) fromthe network periodically or conditional on Q_(i) satisfying thefollowing relationship |Q_(i)−f({Q_(j)}_(j∈{i−N,i−N+1, . . . i−1}))|>δwhere f(⋅) is a function of the last N measurements.

In step S1112, the UE selects the constellation type from thepre-configured list based on the CQI value reported by the network andpreconfigured mapping.

In step S1114, the UE continues data transmission using the selectedmodulation type/order and constellation configuration.

FIG. 12 illustrates a method 1200 according to an embodiment of thepresent principles in which the UE performs constellation adaptationbased on a constellation type configuration received from the network.

In step S1202, the UE utilizes a mandatory standardized modulationtype/order with specific constellation/symbol configuration to reportits supported class(es) or list of supported modulation type(s)/order(s)and corresponding constellation/symbol configuration.

In step S1204, the UE receives a priority order or ranking for thereported list of modulation and constellations configuration (for eachmodulation order), in which a default constellation type (highestpriority) can be one that delivers highest supported DL energyharvesting efficiency, and a lowest priority constellation can be onethat delivers the highest UL transmitted energy per bit for a givenmodulation order.

In step S1206, the UE receives a CQI measurement occasion configurationto facilitate CQI measurements by the network, e.g. a unique ID,modulation type/order, and constellation/symbol configuration.

In step S1208, the UE utilizes the signaled modulation type/order andconstellation/symbol configuration to transmit the configured unique IDat the assigned measurement occasion.

In step S1210, the UE receives a priority value from the networkindicating the modulation type/order and constellation configuration tobe initially utilized for data transmission.

In step S1212, the UE receives data re-transmission request or fails toreceive an ACK within a pre-specified time window for a consecutivespecified signaled/preconfigured number of times.

In step S1214, the UE switches to the next configured constellation andmodulation type on the priority list to re-transmit the data.

In step S1216, the UE continues data transmission using the selectedconstellation and modulation type as long as it does not receive are-transmission request or fails to receive an ACK, cf. step S1212.Otherwise, it repeats step S1214 until the priority list is exhausted oran overall signaled/preconfigured aggregate number of retransmissions isachieved, at which point it declares data transmission/connectionfailure. The method can return to step S1206.

The default (highest priority) constellation configuration, cf. stepS1204, can utilize the zero-reflectance state of the ICM as a point inthe UL signal constellation for efficient DL EH, be a hybridphase-amplitude indirect carrier modulation scheme with the lowestsupported duty cycle factor and the highest supported modulation depthfor efficient DL EH, or be sparse block code based indirect carriermodulation scheme with maximum number of supported zero-reflectancestates per code.

The lowest priority constellation, cf. step S1204, can be a hybridphase-amplitude indirect carrier modulation scheme with the highestsupported duty cycle factor and the lowest supported modulation depth,or be a sparse block code based indirect carrier modulation schemeincluding a phase reversal in the sinusoidal wave packet representingthe non-zero code entries.

FIG. 13 illustrates a method 1300 according to an embodiment of thepresent principles in which the UE performs constellation adaptationbased on an the evaluation of a performance indicator.

In step S1302, the UE utilizes a mandatory standardized modulationtype/order with specific constellation/symbol configuration to reportits supported class(es) or list of supported modulation type(s)/order(s)and corresponding constellation/symbol configuration.

In step S1304, the UE receives a transmission adaptation notificationmessage configuration, e.g. periodicity of transmission or triggeringcriteria and associated parameters, modulation type/order, andconstellation configuration.

In step S1306, the UE receives a configuration of occasions formeasuring a received interrogation signal strength (RISS), e.g. type ofoccasion (standalone measurement occasion or non-standalone, i.e.resources are used for both measurement and UL data transmission),periodicity of occasions, modulation type/order and constellationconfiguration associated with UL transmissions in non-standaloneoccasions.

In step S1308, the UE measures RISS over one or more measurementoccasions and determines the DL energy harvesting efficiency (q)associated with current UL transmission configuration.

In step S1310, the UE receives a data re-transmission request from thenetwork or a notification from its Power Management Unit (PMU) andselects a new constellation from a list of pre-specified ULconstellation types such that the performance indicators(E_(H)−E^(TX))={ηRISS−P_(ICM)}(N/R)>δ and E_(TX)>Δ where P_(ICM) is thepower consumption of the ICM when configured for the new constellation,N is the UL data packet size, R the UL data rate, E_(TX) is the ULtransmitted energy per symbol and δ, Δ are optimization goals that mightbe preconfigured at the UE or signaled by the network as part oftriggering criteria.

In step S1312, the UE uses the preconfigured/signaled transmissionconfiguration and transmits a transmission adaptation notificationmessage indicating the newly selected transmission configuration to beused in the following UL data packets.

In step S1314, the UE transmits UL data packets using the newtransmission configuration.

In an embodiment of a method 2400 according to the present principles,illustrated in FIG. 24 , the UE can perform constellation adaptationafter a data re-transmission request from the network.

In step S2402, the UE utilizes a mandatory standardized modulationtype/order with specific constellation/symbol configuration to reportits supported class(es) or list of supported modulation type(s)/order(s)and corresponding constellation/symbol configuration to the network.

In step S2404, the UE receives a priority order or ranking for thereported list of modulation and constellation configuration (for eachmodulation order), wherein a default constellation type (i.e. withhighest priority) is one that delivers highest supported DL energyharvesting efficiency, and a lowest priority constellation is one thatdelivers the highest UL transmitted energy per bit for a givenmodulation order.

In step S2406, the UE transmits data using the highest priorityconstellation delivering the highest supported DL energy harvestingefficiency.

In step S2408, the UE receives a data re-transmission request or failsto receive an ACK within a pre-specified time window for a consecutivespecified signaled/preconfigured number of times.

In step S2410, the UE switches to the next configured constellation andmodulation type on the priority list to re-transmit the data.

In step S2412, the UE continues data transmission using the selectedconstellation and modulation type as long as it does not receive are-transmission request or receives ACKs, cf. step S1008. Otherwise, itrepeats step S2410 until the priority list is exhausted or an overallsignaled/preconfigured aggregate number of retransmissions is achieved,at which point the UE declares a data transmission/connection failure.

The default (highest priority) constellation configuration for e.g.passive devices in step S2404 can utilize the zero-reflectance state ofthe ICM as a point in the UL signal constellation for efficient DL EH.

The default (highest priority) constellation configuration for e.g.passive devices in step S2404 can be a hybrid phase-amplitude indirectcarrier modulation scheme with the lowest supported duty cycle factorand the highest supported modulation depth for efficient DL EH.

The default (highest priority) constellation configuration for e.g.passive devices in step S2404 can be a sparse block code based indirectcarrier modulation scheme with maximum number of supportedzero-reflectance states per code (i.e. maximum sparsity, highest coderate).

The default (highest priority) constellation configuration for e.g.passive devices in step S2404 can be a dense block code based indirectcarrier modulation scheme with maximum number of supportedzero-reflectance states per code (i.e. minimum density, lowest coderate).

The lowest priority constellation for e.g. passive devices in step S2404can be a hybrid phase-amplitude indirect carrier modulation scheme withthe highest supported duty cycle factor and the lowest supportedmodulation depth.

The lowest priority constellation configuration for e.g. passive devicesin step S2404 can be a dense block code based indirect carriermodulation scheme with maximum number of supported perfect-reflectancestates per code (i.e. maximum density, highest code rate).

The lowest priority constellation configuration for e.g. passive devicesin step S2404 can be sparse block code based indirect carrier modulationscheme with maximum number of supported perfect-reflectance states percode (i.e. minimum sparsity, lowest code rate).

The lowest priority constellation for e.g. passive devices in step S2404can be a sparse block code based indirect carrier modulation schemeincluding a phase reversal in the sinusoidal wave packet representingthe non-zero code entries.

In the method illustrated in FIG. 24 , the UE makes the decision onwhich modulation type/order and associated constellation configurationto be used based on assisting information from the network in the formof priority/ranking list.

FIG. 25 illustrates a method 2500 according to an embodiment of thepresent principles in which the UE performs constellation adaptationbased on a constellation type configuration received from the network.

In step S2502, the UE utilizes a mandatory standardized modulationtype/order with specific constellation/symbol configuration to reportits supported class(es) or list of supported modulation type(s)/order(s)and corresponding constellation/symbol configuration.

In step S2504, the UE receives a priority order or ranking for thereported list of modulation and constellations configuration (for eachmodulation order).

The order or ranking can include a default modulation/constellation type(highest priority) suitable for e.g. battery-less passive devices thatdelivers the highest supported DL energy harvesting efficiency.Alternatively, the order or ranking can include a defaultmodulation/constellation type (highest priority) suitable for e.g.active devices with an on-board battery that delivers the highest ULtransmitted energy per bit for a given modulation order.

The order or ranking can include a lowest priority constellationsuitable for e.g. battery-less passive devices that delivers the highestUL transmitted energy per bit for a given modulation order.Alternatively, the order or ranking can include a lowest priorityconstellation suitable for e.g. active devices with an on-board batterythat delivers the highest supported DL energy harvesting efficiency.

In step S2506, the UE receives a CQI measurement occasion configurationto facilitate CQI measurements by the network, e.g. a unique ID,modulation type/order, and constellation/symbol configuration.

In step S2508, the UE utilizes the signaled modulation type/order andconstellation/symbol configuration to transmit the configured unique IDat the assigned measurement occasion.

In step S2510, the UE receives a priority value from the networkindicating the modulation type/order and constellation configuration tobe initially utilized for data transmission.

In step S2512, the UE receives data re-transmission request or fails toreceive an ACK within a pre-specified time window for a consecutivespecified signaled/preconfigured number of times.

In step S2514, the UE switches to the next configured constellation andmodulation type on the priority list to re-transmit the data.

In step S2516, the UE continues data transmission using the selectedconstellation and modulation type as long as it does not receive are-transmission request or fails to receive an ACK, cf. step S2512.Otherwise, it repeats step S2514 until the priority list is exhausted oran overall signaled/preconfigured aggregate number of retransmissions isachieved, at which point it declares data transmission/connectionfailure. The method can return to step S2506.

The default (highest priority) constellation configuration for e.g.passive devices, cf. step S2504, can utilize the zero-reflectance stateof the ICM as a point in the UL signal constellation for efficient DLEH, be a hybrid phase-amplitude indirect carrier modulation scheme withthe lowest supported duty cycle factor and the highest supportedmodulation depth for efficient DL EH, be a sparse block code basedindirect carrier modulation scheme with maximum number of supportedzero-reflectance states per code (i.e. maximum sparsity, highest coderate), or be a dense block code based indirect carrier modulation schemewith maximum number of supported zero-reflectance states per code (i.e.minimum density, lowest code rate).

The lowest priority constellation for e.g. passive devices, cf. stepS2504, can be a hybrid phase-amplitude indirect carrier modulationscheme with the highest supported duty cycle factor and the lowestsupported modulation depth, a dense block code based indirect carriermodulation scheme with maximum number of supported perfect-reflectancestates per code (i.e. maximum density, highest code rate), a sparseblock code based indirect carrier modulation scheme with maximum numberof supported perfect-reflectance states per code (i.e. minimum sparsity,lowest code rate), or a sparse block code based indirect carriermodulation scheme including a phase reversal in the sinusoidal wavepacket representing the non-zero code entries.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom-access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

1. A method for operation by a wireless transmit/receive unit, WTRU, themethod comprising: selecting a constellation from a set ofconstellations corresponding to a symbol configuration for indirectcarrier modulation, ICM, based on at least one constellation performanceefficacy indicator, each constellation performance efficacy indicatorrespectively corresponding to a constellation of the set ofconstellations; and using the selected constellation and symbolconfiguration, simultaneously harvesting energy and transmitting data.2. The method of claim 1, further comprising evaluating at least one ofthe constellation performance efficacy indicators based on downlinkenergy harvesting, DL EH, efficiency and uplink, UL, data transferreliability for the corresponding constellation.
 3. The method of claim2, further comprising measuring a received signal strength and thedownlink energy harvesting efficiency.
 4. The method of claim 2, whereina constellation performance efficacy indicator comprises at least onequantity ηRISS, PICM and ETX and wherein the constellation is selectedsuch that the at least one quantity comprised in the constellationperformance efficacy indicator satisfies a respective condition ηRISS>ε,PICM<θ, and ETX>Δ, where η is the energy harvesting efficiency, RISS isthe measured received signal strength, PICM is a power consumption ofthe ICM, ETX is an uplink transmitted energy per symbol and θ, ε, and Δare goal values.
 5. The method of claim 4, wherein the constellation isselected such that (ηRISS−PICM)(N/R)>δ and the second efficacy indicatorETX>Δ, where N is an uplink data packet size, R is an uplink data rateand δ is a goal value.
 6. The method of claim 1, further comprisingselecting the symbol configuration.
 7. The method of claim 1, furthercomprising transmitting an indication of the selected constellation andsymbol configuration.
 8. The method of claim 1, wherein theconstellation defines an arrangement of constellation points.
 9. Themethod of claim 1, wherein the symbol configuration defines a number ofbits per symbol.
 10. The method of claim 1, wherein the constellation isdetermined by indirect carrier modulator impedance states.
 11. Awireless transmit/receive unit, WTRU, comprising: an antenna configuredto transmit data; an energy harvester configured to harvest energy; andat least one hardware processor configured to select a constellationfrom a set of constellations corresponding to a symbol configuration forindirect carrier modulation, ICM, based on at least one constellationperformance efficacy indicator, each constellation performance efficacyindicator respectively corresponding to a constellation of the set ofconstellations; wherein the selected constellation and symbolconfiguration are used to simultaneously harvest energy and transmitdata.
 12. The WTRU of claim 11, wherein the at least one hardwareprocessor is further configured to evaluate at least one of theconstellation performance efficacy indicators based on downlink energyharvesting, DL EH, efficiency and uplink, UL, data transfer reliabilityfor the corresponding constellation.
 13. The WTRU of claim 12, whereinthe at least one hardware processor is further configured to measure areceived signal strength and the downlink energy harvesting efficiency.14. The WTRU of claim 12, wherein a constellation performance efficacyindicator comprises at least one quantity ηRISS, PICM and ETX andwherein the at least one hardware processor is configured to select theconstellation such that the at least one quantity comprised in theconstellation performance efficacy indicator satisfies a respectivecondition ηRISS>ε, PICM<θ, and ETX>Δ, where η is the energy harvestingefficiency, RISS is the measured received signal strength, PICM is apower consumption of the ICM, ETX is an uplink transmitted energy persymbol and θ, ε, and Δ are goal values.
 15. The WTRU of claim 14,wherein the at least one hardware processor is configured to select theconstellation such that (ηRISS−PICM)(N/R)>δ and the second efficacyindicator ETX>Δ, where N is an uplink data packet size, R is an uplinkdata rate and δ is a goal value.
 16. The WTRU of claim 11, wherein theat least one hardware processor is further configured to select thesymbol configuration.
 17. The WTRU of claim 11, wherein the at least onehardware processor is further configured to transmit, through theantenna, an indication of the selected constellation and symbolconfiguration.
 18. The WTRU of claim 11, wherein the constellationdefines an arrangement of constellation points.
 19. The WTRU of claim11, wherein the symbol configuration defines a number of bits persymbol.
 20. The WTRU of claim 11, wherein the constellation isdetermined by indirect carrier modulator impedance states.